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| Home > Publications database > Lipid Biomarkers in Lacustrine Sedimentary Archives - An Inventory and Evaluation as Proxis for Environmental and Climate Change |
| Dissertation / PhD Thesis/Book | PreJuSER-38076 |
2003
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/163
Report No.: Juel-4121
Abstract: With the growing understanding of human influence on the Earth system, an increasing number of scientific investigations focuses on vegetation responses to changing environmental and/or climatic conditions. A detailed prediction, how e.g. increasing atmospheric temperatures affect the composition of terrestrial and aquatic vegetation composition, however, remains difficult without a detailed knowledge of comparable changes during the past. A number of archives recording changes in environmental and/or climatic conditions under varying temporal integration and resolution have been evaluated up to now. Changing conditions are, however, not recorded directly. Measured proxyparameters need to be interpreted and correlated to environmental and climatic parameters. Lacustrine sedimentary archives are generally regarded as excellent archives in terms of paleolimnology. Sediments of two maar lakes, a special form of crater lakes, have been selected as sedimentary records for the study presented here. The lipid composition of Lake Holzmaar and Lake Meerfelder Maar sediments has been evaluated with respect to varying proportions of autochthonous and allochthonous organic matter contribution. In a second step, detected changes in organic matter contributing sources were correlated to environmental and climatic changes. In order to overcome the reginal scale of this investigation, sediments from Lake Großer Treppelsee, eastern Brandenburg, were added to this study and investigated under the same programme. A selected section of Lake Meerfelder Maar sedimentary profile including the Younger Dryas cold period and the transition to the early Holocene was finally analysed under highest achievable temporal resolution to detect vegetation response to climatic change in high detail. Bulk organic geochemical parameters (TOC, TIC, TS, TN, HI, OI) were measured as fundamental data. Lipids were extracted using a flow blending method and further separated into compound specific fractions using a semi-preparative liquid-chromatographic separation procedure. The fractions of aliphatic hydrocarbons, carboxylic acids and alcohols plus sterols were inventoried by means of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). GC-MS was performed in order to identify individual compounds by interpretation of mass spectra and comparison with authentic standards and/ or literature data; GC was performed for quantification of these compounds. A compelling prerequisite for the connection between lipid distributions and environmental and/ or climatic conditions is a good preservation of the investigated sedimentary matter. Using three different parameters, TOC/ TS, Pristane/ Phytane and URFA ratios, it could be confirmed that the investigated sedimentary records are well preserved. A partial loss of organic matter could not be excluded, however, the organic matter composition was found to be not overprinted by diagenetic effects by far. It was therefore concluded, that changes in the lipid composition are related to changes in the organic matter contributing community in and around the investigated lakes as a result of changing environmental and/ or climatic conditions. [...]
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